Superregenerative receiver



March 17, 1935. R w. GEORGE zms saz SUPERREGENERATIVE RECEIVER FiledJan. 28, 1932 \NPUT i0 INVENTOR R. W. GEORG ATTORNEY Patented Mar. 17,1936 Radio Corporation of America, a corporation of Delaware ApplicationJanuary 28, 1932, Serial No. 589,392

- Claims.

This invention relates to regenerative receiving systems, and moreparticularly to an improved type of super-regenerative receivingcircuit.

In United States Patent No. 1,982,694, granted 5 December 4, 1934, toWalter Van B. Roberts, there is disclosed a method of securing highamplification in a super-regenerative system without building upsustained oscillations. Briefly, the method disclosed in theaforementioned application comprises periodically reversingthe phase ofthe feed-back in the system for rapidly quenching radio frequencyoscillations during the damping period. The particular embodimentdisclosed therein consists of a pair of space discharge devices, one ofthe devicesintermittently functioning as an oscillator generaton theother device intermittently and alternately with the first device actingto quench oscillations prior to the instant when oscillations built upby the oscillator generator would otherwise attain an undesirableamplitude.

Reference is also made to United States Patent No. 1,948,315, grantedFebruary 20, 1934 to Walter Van B. Roberts, wherein there are disclosedvarious embodiments for producing super-regeneration in a receivingsystem including a pair of oppositely connected space discharge devices,the basic method employed in each of these embodiments consisting ofapplying simultaneously both signal energy and a low frequencyinterrupting voltage in a differential manner to the devices, the commonoutput circuit being coupled to the common input circuit of the devices.It is pointed out in this patent, supra, that the embodiments disclosedtherein can be considered as balanced modulator circuits, wherein asignal collecting circuit and a relatively low frequency modulatingvoltage source are provided with additional means for feeding back tothe signal circuit the side bands at radio frequencies produced bymodulation of signal voltages. In particular, the patentee discloses asuper-regenerative arrangement wherein a source of interruptingfrequency is coupled directly across the input of a pair of oppositelyconnected space discharge devices, a common feed-back reactance in thecommon output circuit of the device being utilized to couple the outputcircuit to reactances in the common input circuit of the devices. Whilevarious advantages are stated as being secured by means of theaforementioned super-regenerative embodiments, further experimentationand development of this type of super-regenerative circuit has resultedin additional advantages.

It is an object of the present invention to provide a super-regenerativereceiving system wherein t-helow frequency circuits can have no possibledetrimental effect on the high frequency circuits, and this is attainedby coupling the relatively low frequency quenching interrupter to thecathodes of the electron discharge device.

An advantage of the present invention is that the whole arrangement ofparts can be made relatively simple, and the symmetry and efiiciency ofthe grid circuit maintained more easily than heretofore possible.

A further advantage of this invention is that the source of interruptingfrequency may be placed in a remote and more suitable location thanimmediately adjacent the main portion of the super-regenerative circuit.

The invention is described in more detail in the following descriptionwhich is accompanied by a single drawing, wherein there is shown a superregenerative receiving circuit embodying ,the principles of the presentinvention. Essentially, the circuit comprises a pair of electrondischarge devices l l and I2 of the indirect heater type which havetheir respective corresponding electrodes connected together, and asource of quenching frequency current l8 coupled to the cathodesthereof. Although the indirect heater type of tube is shown in thedrawing, it is to be understood, of course, that the showing is merelyfor purposes of illustration since any other suitable electron dischargetube, such as the directly heated three element tube, the tetrode orpentode may be used instead, if desired.

The incoming high frequency signals are received over input coil it!which is coupled to the tubes H and I2 through resonant circuit l3, l4tuned to the input signal frequency. The electron discharge devices Hand i2 have connected to their anode circuits a feed-back coil 15 whichis coupled to the grids of the tubes through inductance coil l3.Positive potential is applied to the anodes of the tubes, which aredirectly connected together, from a source 20. The positive terminal ofsource 20 is connected in series with feed-back coil l5 through a signalutilization means 2!, the latter comprising, for example, a pair ofheadphones. The fixed condensers Hi, i! and 22 are radio frequencyby-pass condensers. A keying or relatively low frequency quenchingoscillator 58 is shown coupled to the cathodes l9, I9 of the tubesthrough coils 23, 24 for varying periodically the potential of thecathodes with respect to the grids.

Coils l3 and 23 are connected at their center points to ground andbattery respectively and thus permit the application simultaneously ofboth signal energy and the relatively low frequency interrupting voltageto devices II and I2 in a differential manner.

Quenching frequency oscillator l8 preferably functions at an audiblefrequency of about 8000 cycles per second. In practice it has been foundthat a wide range of quenching frequencies may be used satisfactorily.For example, when this super-regenerative circuit is employed with anultra short wave receiving circuit of the type described in my UnitedStates Patent No. 2,011,942, granted August 20, 1935, a quenchingfrequency of the order of 25 kilocycles may be used with excellentresults.

Signal input circuit It may be connected directly to an antenna circuitor coupled to the output of a stage of amplification disposed betweenthe antenna and the input circuit of tubes II and I2. Of course, ifdesired, a source of high intermediate frequency current produced byanother receiver may be placed between the antenna and the signal inputcircuit of the superregenerative circuit. In other words, it is to beclearly understood that the circuit shown in the drawing lends itselfreadily to amplification of radio frequencies regardless of the sourceof such radio frequencies.

The manner of coupling the quenching oscillator l8 to the cathodes, asherein described, in-

stead of to the control electrodes of the tubes, as has been doneheretofore, has the advantage of giving simplicity and symmetry to thecircuit and at the same time maintaining the efficiency of the gridcircuit. Inasmuch as the potentials between the grids and cathodes arekeyed or changed by and at the quenching frequency, the operation of thecircuit is equivalent to that when the relatively low quenchingfrequency is coupled directly to the grid circuit, which is described indetail in the aforementioned Roberts Patent No. 1,948,315.

It is to be clearly understood that this invention is not limited to acircuit employing only two tubes, but may be applied to anysuper-regenerative circuit. Further, this particular arrangement may beadvantageously. used in modulating transmitters and coupling toamplifiers. In such arrangements, if desired, the symmetry of thecircuit may be maintained by connecting suitable impedance matchingdevices in the oathode circuits without affecting the plate or gridcircuits.

I claim:

1. In combination, in a super-regenerative receiver, a pair of electrondischarge tubes each having a cathode, anode, and control electrode,means for connecting the corresponding respective electrodes together,an input circuit connected to said control electrodes in oppositesenses, a common output circuit connected to the anodes of said tubesand coupled to said input circuit, a source of relatively low frequencycurrent, and means for differentially coupling said source to thecathodes of said tubes.

2. A super-regenerative receiver circuit comprising a pair of electrondischarge devices each having an anode, grid, an electron emittingelectrode, and a heating element, means for connecting the correspondingrespective electrodes of said devices together, a source of directcurrent heating energy for the heating elements of said devices, asource of relatively low frequency current, and means for differentiallycoupling said last source to the electron emitting electrodes of saiddevices.

3. A super-regenerative receiver circuit comprising an indirectly heatedelectron discharge device having a plurality of electrodes including anelectron heating element and an electron emitting element, input andoutput circuits for said devices coupled together, a source of directcurrent heating energy for the heating element of said electrondischarge device, a source of periodic interrupting current, and meansfor coupling said last source to the electron emitting element of saiddevice.

4. A super-regenerative receiver comprising a pair of electron dischargedevices having anode, cathode and control electrodes, means forconnecting the respective corresponding electrodes of said devicestogether, and means for differentially exciting the cathodes of saidpair of devices comprising a source of interrupting current.

5. A super-regenerative receiver circuit comprising a pair of indirectcathode heater-type tubes having anode, grid, heating and electronemitting elements, means for connecting said corresponding elementstogether, and means for differentially exciting the electron emittingelements of said pair of tubes.

RALPH W. GEORGE.

